While many cancers are treatable by chemotherapeutic agents, a significant number of cancers are intrinsically drug resistant and others acquire resistance during or following chemotherapy. Cancers frequently are resistant to more than one type of drug. This phenomenon is called multidrug resistance or MDR. Consequently, there is a great need for compositions and methods that can be used in addition to, or as alternatives to, chemotherapy for the treatment of cancer.
A major clinical problem of cancer is metastasis. By the time that the primary tumor is identified and localized, seed cells often have escaped and migrated or metastasized to other organs in the body where they establish secondary tumors. Surgical procedures are rarely sufficient to cure a cancer because even after the primary tumor is removed multiple secondary tumors survive and proliferate. Consequently, there exists an immediate and pressing need for techniques of eradicating secondary tumors that already exist.
Cancer cells that escape the primary tumor are usually carried in the venous and lymphatic circulation until they lodge in a downstream capillary bed or lymph node. However, only 1 in 10,000 of the cancer cells that escape the primary tumor survive to establish a secondary tumor. Successful cancer cells are those that find a favorable environment for survival and growth. The favorable environment include hormones and growth-promoting factors. Stimulating factors include local growth factors, hormones produced by the host, and autostimulating growth factors produced by the tumor cells themselves. Consequently, there is an immediate and pressing need for techniques capable preventing or inhibiting metastasis of cancer and the formation of secondary tumors.
Additionally, many other hyperproliferative disorders exist. Hyperproliferative disorders are caused by non-cancerous (i.e. non-neoplastic) cells that overproduce in response to a particular growth factor. Examples of such hyperproliferative disorders include diabetic retinopathy, psoriasis, endometriosis, macular degenerative disorders and benign growth disorders such as prostate enlargement and lipomas.
It is known that many new cancers are initiated, and existing cancers and hyperproliferative disorders stimulated, by growth factors that affect either the cancer cell itself or normal tissue around the cancer that facilitate survival of the cancer cell (i.e., angiogenesis factors). There is a direct correlation between the circulating level of certain growth factors and cancer proliferation. A potential method of treatment would be to regulate the level of circulating growth factors in a patient to prevent cancers initiation or recurrence and to reduce or eliminate existing cancers. What is needed, therefore, are compositions that remove the appropriate growth factors from circulation or inhibit the growth-promoting activity of growth factors.